United was plagued with a huge issue even before dragging a customer off a plane

Travelers line up at a United Airlines check-in counter at Hartsfield–Jackson Atlanta International Airport Wednesday, July 8, 2015, in Atlanta. All United Continental flights in the U.S. were grounded Wednesday due to computer problems. Just shy of two hours after the problems began, the Federal Aviation Administration lifted the ground stop order. United said it was recovering from a "network connectivity issue" and restoring regular flight operations.
David Goldman/AP Photo

United is America's worst legacy airline, according to a recent survey.

The survey, which was conducted by the American Customer Satisfaction Index (ACSI), found that United was the lowest ranking legacy airline, with a score of 70 points out of a 100. However, the airline did improve from its 2016 score of 68 points.

Considering the recent turmoil surrounding the company, this may not be that surprising. But the survey, which polled 180,000 people over 12 months, was actually completed in March before the incident involving a passenger being dragged off a United flight.

The incident happened on April 9 aboard a plane in Chicago heading to Louisville. The passenger, 69-year-old David Dao, was dragged off the plane by Chicago Aviation police officers after refusing to give up his seat on the plane. A fellow passenger recorded the incident and the video quickly went viral.